Introducing the IFRAO Standard Scale

The IFRAO (International Federation of Rock Art Organisations) Standard Scale was first proposed in IFRAO
Report No. 6 (Bednarik 1991). Consultation of researchers and various specialists in the following years has
led to progressive evolution of the design (cf. Rock Art Research 8: 156) until it was finalised in 1993. The
Australian Institute of Aboriginal and Torres Strait Islander Studies then made available a grant to meet the
cost of producing the Scale, through its Rock Art Protection Program. The Institute realised the enormous
advantages of such a measure — in documentation, computerisation, and the study of rock art and patination

Purpose of the Scale
We know that there are many millions of photographs and colour transparencies of rock art in existence
world-wide: in my estimation at least twenty millions. Many archives have in the order of hundreds of
thousands of images, while thousands of individual researchers each possess collections of many thousands of
colour slides or photographs. We also know that this enormous collective record is irreplaceable, and yet it
is doomed to eventual destruction. No known photographic dye is fadeproof, and we still lack any form of
permanent photographic or digitised storage of imagery (Dickman 1984). In short, this enormous effort of
creating a visual record of world rock art is ultimately in vain. Even with rapid rock art deterioration it
will be survived by most rock art, fortunately. But there is a simple way of rendering this massive record
permanently useful: digitised colour re-constitution or reconstruction.
In scientific photography it is essential to know the size of an image, and for this purpose, Taylor et al.
(1979) designed a simple ten-centimetre scale for rock art recording. A scale has other roles too. It serves
as a general indication of a photograph’s sharpness, by showing how well it was focused and processed. Manual
focusing is often difficult with rock art, because of the typical lack of straight or well-defined lines, and
the operation of a camera with viewfinder focusing is much easier by selecting one of the lines on a scale.
More important than the black and white scale markings are the colour blots. The colour properties of an
object are always distorted in a photograph, by such factors as optics, film type, paper type, temperature
and, most particularly, lighting conditions. Therefore a colour photograph cannot be expected to be a true
record of chroma, value and hue. However, by checking the colour distortion on a scale photographed with the
rock art we can obtain an indication of its severity. Some rock art researchers (a very tiny minority) have
been using a variety of colour scales, including the Munsell Soil Colour Chart, the Kodak Colour Separation
Guide, the Letraset Pantone colour chart and a variety of others. These colour standard charts are all
expensive, they are all different, and standardisation would obviously be desirable here.
The main reason for needing a standard photographic scale, however, is its function as a
COLOUR CALIBRATION DEVICE for a variety of computer-supported uses.
Electronic colour enhancement methods have been used in rock art studies for many years (Rip 1983).
In 1994, electronic colour re-constitution of rock art images was achieved at the National Museum of Man
in Bhopal, India, calibrated with the IFRAO Standard Scale as the profile device (Bednarik and Seshadri 1995).
This has led to the development of colour-reconstitution software at the Museum.
The original colour values of colour-distorted and even faded rock art photographs can now be automatically
re-constituted almost in an instant. The only precondition is that the photograph must bear a colour standard
against which the computer can calibrate. The greatest advantage is that the computer does not recover the
colour properties of the original photograph, before it faded, but goes beyond that — all the way back to the
true colour of the rock art image at the moment it was photographed! It re-constitutes the actual colour
properties of the subject at the time, even if this was several decades earlier. Colour re-constitution thus
compensates for photographic distortion as well as for the subsequent fading of dyes.
This technology opens enormous possibilities in research, recording, documentation storage, computerised image
manipulation, publishing and conser-vation studies. For instance, such techniques can facilitate
mathematically precise monitoring of deterioration of rock art pigment or patinae over any period of time
(Pager 1992; Ward and Maggs 1994). They permit the recovery of objective colour information, free of the
‘technical subjectivity’ of conventional photography. They facilitate the digitisation of real colour
information, which can then be used in many ways: it can be permanently stored, it can be used as the basis of
enhancement procedures (Rip 1989), or it can be cross-checked in intra- and inter-site studies for various
purposes by engaging computer search functions. Such information can also be used in conservation, retouch,
graffiti and lacunae repair, comparative pigment studies, sourcing studies, dating work, recovery of very
faint images, printing of colour plates and so forth. It provides a reliable and standardised base for
numerous applications, and while many of the technologies required may not yet have been developed, it is most
reasonable to expect that they will be available within a few years. All that is required at this stage is
that every photograph taken of rock art for scientific purposes must hear the same colour calibration standard
The long-term effect of the use of the IFRAO Standard Scale will be a standardisation of the photographic
record of world rock art. Our archival record will become a permanent record by virtue of its retrievability.
The greatest fear of all rock art students, that the art will deteriorate beyond archival recovery, can be met
by the knowledge that the susceptibility of our photographic record to colour calibration will lead to an
‘ultimate conservation method’. We will have the means of preserving rock art in pristine condition forever,
at least in our archives.

Use of the IFRAO Standard Scale
The IFRAO Standard Scale bears the printing date and will be periodically reprinted to guard against it
fading. It should be stored in a dark, dry and cool place when not in use. It includes a grey scale for
comparing tone values. The patches correspond with reflection densities of 0.0, 0.70 and 1.60 respectively.
The Scale must never be placed over rock art, or very close to a motif. Preferably it should not be attached
to the rock face. In vertical or overhead locations, the Scale should be hand held. Only where definitely
undecorated and structurally sound rock surface is available may the use of small double-sided adhesive pads
be considered, or the insertion of small metal pins through the Scale to affix it to soft rock surfaces (e.g.
in limestone caves); but this is to be avoided whenever possible.
The Scale should be positioned parallel to the predominant plane of the rock art motif and the same distance
from the camera lens. Ensure that the lighting source is not directly reflected by the Scale. One Scale should
be used for distances of up to 1.5 m. Between 1.5 and 4.5 m, two Scales are required. The Scale cannot be used with precision at distances exceeding 4.5 m, using lenses of standard focal length. Best results will be
achieved at distances of under 1 m. Where artificial lighting is required, place the Scale on upper left
corner and light the image from same direction. However, natural lighting is preferred to artificial. The
small scale on the left-hand end of the IFRAO Scale is intended for close-up photographs. For best digital
results, slides or negatives are preferred to prints.
The IFRAO Standard Scale is distributed free to all rock art researchers of the world (the members of the
thirty IFRAO-affiliated organisations). In addition, it is rapidly being adopted by specialists in various
other fields. Specimens of the Scale are available from the IFRAO Convener’s office (P.O. Box 216, Caulfield
South, Vic. 3162, Australia). The sale of the IFRAO Scale for profit is not permitted. The Scale is not
subject to copyright within IFRAO and may be reproduced by any organisation affiliated with IFRAO — but again,
not for profit.

I express my gratitude to the sponsor who underwrote the initial pro-duction costs of the IFRAO Standard
Scale, the Australian Institute of Aboriginal and Torres Strait Islander Studies, Canberra, Australia. I also
thank the Australia-India Council, Canberra, for supporting the work at the National Museum of Man in India in

IFRAO Convener

BEDNARIK, R. G. 1991. The IFRAO Standard Scale. Rock Art Research 8: 78-8.
BEDNARIK, R. G. and K. SESHADRI 1995. Digital colour re-constitution in rock
art photography. Rock Art Research 12: 42-51.
DICKMAN, J. L. 1984. An image digitising and storage system for use in rock art
research. Rock Art Research 1: 25-35.
PAGER, S.-A. 1992. Deterioration of the rock paintings in Botha’s Shelter, Ndedema Gorge.
Pictogram 4(2): 1-2.RIP. M. R. 1983. Digital recording and image processing of rock art
by computer. South African Archaeological Bulletin 38: 77-9.
RIP. M. R. 1989. Colour space transformations for the enhancement of rock art images
by computer. Rock Art Research 6: 12-16.
TAYLOR. J. M.. W. BOKMAN and I. N. M. WAINWRIGHT 1979. Rock art conservation:
some realities and practical considera-tions. In D. Lundy (ed.).
CRARA.77. Papers from the Fourth Biennial Conference of the Canadian Rock
Art Research Associates pp. 293-323. Heritage Record No. 8, The British Columbia Provincial Museum, Victoria.
WARD. V. and T. MAGGS 1994. Early copies as an indicator of rock art deterioration. Pictogram 6(2): 36-7.